What is causing my Ford Focus to overheat?

I have a 2015 Ford Focus SE and recently, I've noticed that my car's temperature gauge goes into the red when I'm stuck in traffic or driving at low speeds. What could be causing this issue and how can I fix it?

It's possible that your car's radiator fan is not functioning properly. Have a mechanic check it out and replace it if necessary.

Make sure your coolant levels are topped off and that there are no leaks in the system. If everything looks good, you may need to replace your thermostat.

Have you changed your oil recently? Old oil can cause your engine to overheat. Consider getting an oil change.